The development of adaptive body reactions after intensive physical loading]

The dependence between the activity parameters of muscarine antagonists in the prevention of haloperidol catalepsy in rats and those in tests characterizing the interaction of ligands and various subtypes of m-cholinoceptors was studied. It was established by constructing the mathematical dependence that blockade of m1-cholinoceptors increases, while that of m2-cholinoceptors reduces the antiparkinsonian activity of the drugs. The activity of the muscarine antagonist pentiphan in the prevention of haloperidol-induced catalepsy in rats exceeds the activity of such traditional antiparkinsonian drugs as cyclodol and amedin.     

Dissecting cAMP binding domain A in the RIalpha subunit of cAMP-dependent protein kinase. Distinct subsites for recognition of cAMP and the catalytic subunit

The two gene-duplicated cAMP binding domains in the regulatory subunits of cAMP dependent protein kinase are each comprised of an A helix, an eight-stranded beta-barrel, and a B and C helix (1). The A domain is required for high affinity binding to C, while the B domain regulates access to the A domain. Using a combination of a yeast two-hybrid screen coupled with deletion analysis, cAMP binding domain A of RI was dissected into two structurally and functionally distinct subsites, one that binds cAMP and another that binds the C subunit. The minimum stable subdomain required for binding to C in the 1-3 micromolar range is composed of residues 94-169, while residues 236-244, mapped to the C helix of cAMP binding domain A, were defined as a second surface necessary for high affinity (5-10 nanomolar) binding to C. This portion of the C helix, due to its position directly between the two subsites, serves as a molecular switch for either a cAMP-bound conformation or a C-bound conformation and can thus modulate interactions of cAMP binding domain A with cAMP, with C, and with cAMP binding domain B.     

Evidence for a salt bridge between transmembrane segments 5 and 6 of the yeast plasma-membrane H+-ATPase

The plasma-membrane H+-ATPase of Saccharomyces cerevisiae, which belongs to the P2 subgroup of cation-transporting ATPases, is encoded by the PMA1 gene and functions physiologically to pump protons out of the cell. This study has focused on hydrophobic transmembrane segments M5 and M6 of the H+-ATPase. In particular, a conserved aspartate residue near the middle of M6 has been found to play a critical role in the structure and biogenesis of the ATPase. Site-directed mutants in which Asp-730 was replaced by an uncharged residue (Asn or Val) were abnormally sensitive to trypsin, consistent with the idea that the proteins were poorly folded, and immunofluorescence confocal microscopy showed them to be arrested in the endoplasmic reticulum. Similar defects are known to occur when either Arg-695 or His-701 in M5 is replaced by a neutral residue (Dutra, M. B., Ambesi, A., and Slayman, C. W. (1998) J. Biol. Chem. 273, 17411-17417). To search for possible charge-charge interactions between Asp-730 and Arg-695 or His-701, double mutants were constructed in which positively and negatively charged residues were swapped or eliminated. Strikingly, two of the double mutants (R695D/D730R and R695A/D730A) regained the capacity for normal biogenesis and displayed near-normal rates of ATP hydrolysis and ATP-dependent H+ pumping. These results demonstrate that neither Arg-695 nor Asp-730 is required for enzymatic activity or proton transport, but suggest that there is a salt bridge between the two residues, linking M5 and M6 of the 100-kDa polypeptide.     

A new method to estimate parameters of linear compartmental models using artificial neural networks

At present, the preferred tool for parameter estimation in compartmental analysis is an iterative procedure; weighted nonlinear regression. For a large number of applications, observed data can be fitted to sums of exponentials whose parameters are directly related to the rate constants/coefficients of the compartmental models. Since weighted nonlinear regression often has to be repeated for many different data sets, the process of fitting data from compartmental systems can be very time consuming. Furthermore the minimization routine often converges to a local (as opposed to global) minimum. In this paper, we examine the possibility of using artificial neural networks instead of weighted nonlinear regression in order to estimate model parameters. We train simple feed-forward neural networks to produce as outputs the parameter values of a given model when kinetic data are fed to the networks' input layer. The artificial neural networks produce unbiased estimates and are orders of magnitude faster than regression algorithms. At noise levels typical of many real applications, the neural networks are found to produce lower variance estimates than weighted nonlinear regression in the estimation of parameters from mono- and biexponential models. These results are primarily due to the inability of weighted nonlinear regression to converge. These results establish that artificial neural networks are powerful tools for estimating parameters for simple compartmental models.     

Effect of propranolol and nifedipine on maximal electroshock-induced seizures in mice: individually and in combination

To clarify the influence of the head-up position on cerebral oxygen metabolism during laparoscopy with CO2 insufflation in 12 patients who underwent laparoscopic cholecystectomy, changes in the concentrations of cerebral oxyhemoglobin (HbO2), deoxyhemoglobin (Hb), total hemoglobin (total Hb) and oxidized cytochrome aa3 (Cyt aa3) were measured by use of near-infrared laser spectroscopy. Anesthesia was maintained with nitrous oxide (66%), oxygen, and sevoflurane. Pneumoperitoneum was maintained at an intraabdominal pressure of 10-12 mm Hg by use of CO2. Minute ventilation was adjusted to maintain end-tidal CO2 tension (P(ET)CO2) between 35 and 40 mm Hg during the procedure. Patients were moved from supine to the head-up (20 degree) position before intraabdominal manipulation. The concentration of HbO2 decreased significantly when patients were moved to the head-up position and 30 min thereafter. It remained significantly low after they were returned to the supine position and at the end of surgery. The concentration of Hb was unchanged during the study. Therefore, the concentration of total Hb decreased significantly when patients were moved to the head-up position, as well as 30 min thereafter. It remained significantly low after they were returned to the supine position and at the end of surgery. The concentration of Cyt aa3, however, did not change significantly during the study. These results suggest that the head-up position during laparoscopic cholecystectomy decreases cerebral HbO2 and total Hb.     

Properties of the catalytic center of a secretory 28kDa protein (1-cys peroxiredoxin) from rat olfactory epithelium

BACKGROUND: Percutaneous mitral valvuloplasty with the Inoue balloon is conventionally performed with double vascular access: arterial and venous. However, in patients with a good echogenic window it may be performed with venous access only and the procedure monitored by 2D-echocardiography and colour flow mapping. This should result in early ambulation and hospital discharge with reduced arterial complications. AIMS: To compare retrospectively the immediate results of percutaneous mitral valvuloplasty with the Inoue balloon in two groups of patients: Group I: venous access only (no arterial access, n = 102) and Group II: conventional double vascular access (arterial and venous access, n = 275). METHODS AND RESULTS: The baseline characteristics of the two groups were comparable for age, sex, clinical, echocardiographic, radiological and haemodynamic variables. The mitral valve area (Group I: 1.1 +/- 0.3 to 1.85 +/- 0.5 cm2 vs Group II: 1.05 +/- 0.2 to 1.85 +/- 0.5 cm2, P = ns) and transmitral gradient (Group I: 11 +/- 4 to 4.7 +/- 2 mmHg vs Group II: 12 +/- 4 to 4.8 +/- 2 mmHg, P = ns) before and after mitral valvuloplasty were not statistically different. A good immediate result, defined as mitral valve area > 1.5 cm2 and mean mitral gradient < 5 mmHg with mitral regurgitation < or = 2+ at the end of the procedure, was observed in 77% of the cases in the venous-only group and 79% in the double access group (P = ns). The incidence of severe mitral regurgitation (Grade III or IV) was not statistically significant. Procedural duration (71 +/- 24 min vs 109 +/- 26 min, P < 0.01), fluoroscopic time (12.5 +/- 5.5 min vs 18.5 +/- 6 min, P < 0.01) and hospital stay (2.8 +/- 1.5 days vs 4.8 +/- 2.6 days, P < 0.001) were significantly shorter in the venous-only group than in the conventional Inoue series. CONCLUSION: Single venous access balloon mitral valvuloplasty is as equally safe and effective as double vascular access. The additional advantages of single venous access are shorter procedural duration, fluoroscopic time and hospital stay. We recommend that it be performed by an experienced operator (minimum of 100 trans-septal punctures) in patients without major thoracic deformity and a good echogenic window.     

Identification of amino acid residues in a class I ubiquitin-conjugating enzyme involved in determining specificity of conjugation of ubiquitin to proteins

The ubiquitin pathway is a major system for selective proteolysis in eukaryotes. However, the mechanisms underlying substrate selectivity by the ubiquitin system remain unclear. We previously identified isoforms of a rat ubiquitin-conjugating enzyme (E2) homologous to the Saccharomyces cerevisiae class I E2 genes, UBC4/UBC5. Two isoforms, although 93% identical, show distinct features. UBC4-1 is expressed ubiquitously, whereas UBC4-testis is expressed in spermatids. Interestingly, although these isoforms interacted similarly with some ubiquitin-protein ligases (E3s) such as E6-AP and rat p100 and an E3 that conjugates ubiquitin to histone H2A, they also supported conjugation of ubiquitin to distinct subsets of testis proteins. UBC4-1 showed an 11-fold greater ability to support conjugation of ubiquitin to endogenous substrates present in a testis nuclear fraction. Site-directed mutagenesis of the UBC4-testis isoform was undertaken to identify regions of the molecule responsible for the observed difference in substrate specificity. Four residues (Gln-15, Ala-49, Ser-107, and Gln-125) scattered on surfaces away from the active site appeared necessary and sufficient for UBC4-1-like conjugation. These four residues identify a large surface of the E2 core domain that may represent an area of binding to E3s or substrates. These findings demonstrate that a limited number of amino acid substitutions in E2s can dictate conjugation of ubiquitin to different proteins and indicate a mechanism by which small E2 molecules can encode a wide range of substrate specificities.     

Serum antibodies reacting with subgingival species in refractory periodontitis subjects

The purpose of this investigation was to compare the levels of serum IgG antibody to 85 subgingival species in 32 refractory periodontitis, 56 successfully treated, and 33 periodontally healthy subjects. Refractory subjects showed mean full mouth attachment loss and/or >3 sites showing attachment loss >2.5 mm within 1 year after 2 treatment modalities, scaling and root planing and surgery plus systemically administered tetracycline. Successfully-treated subjects showed mean attachment level gain and no sites with attachment loss >2.5 mm, 1 year post-therapy. Periodontally healthy subjects exhibited no pocket or attachment level >3 mm, and no evidence of progressing attachment loss during 1 year of monitoring. Baseline serum was obtained from each subject and tested against 85 subgingival species, including reference strains and strains isolated from refractory subjects, using checkerboard immunoblotting. Significance of differences in levels of serum antibody among groups were sought using the Kruskal-Wallis test. Refractory subjects constituted a heterogeneous group based on their serum antibody response to subgingival species. Some individuals had antibody reactions to many subgingival species, while other subjects showed fewer or low numbers of responses. On average, refractory subjects exhibited higher numbers and levels of serum antibody reactions to a wide range of subgingival species than successfully treated or periodontally healthy subjects. Differences in serum antibody among clinical groups were more striking at higher threshold levels of antibody (>50 microg/ml and > 100 microg/ml). The data showed that a subject was 10.1 x more likely to be refractory if the subject exhibited antibody reactions with >9 subgingival species at >50 microg/ml (p<0.001, after adjusting for multiple comparisons). Serum antibody to a subset of the test species differed among the clinical groups. Porphyromonas gingivalis, Bacteroidesforsythus, and some strains isolated from refractory subjects (a novel Neisseria sp., Enterococcus faecalis, Prevotella loescheii and Prevotella oulora) elicited high serum antibody in the successfully treated and refractory subjects. High levels of serum antibody to a Microbacterium lacticum-like organism, Streptococcus oralis, Streptococcus constellatus, Actinobacillus actinonmycetemcomitans serotype c and Haemophilus aphrophilus significantly increased the likelihood of a subject being refractory to conventional periodontal therapy.     

Linking service climate and customer perceptions of service quality: test of a causal model

A set of foundation issues that support employee work and service quality is conceptualized as a necessary but not sufficient cause of a climate for service, which in turn is proposed to be reflected in customer experiences. Climate for service rests on the foundation issues, but in addition it requires policies and practices that focus attention directly on service quality. Data were collected at multiple points in time from employees and customers of 134 branches of a bank and analyzed via structural equation modeling. Results indicated that the model in which the foundation issues yielded a climate for service, and climate for service in turn led to customer perceptions of service quality, fit the data well. However, subsequent cross-lagged analyses revealed the presence of a reciprocal effect for climate and customer perceptions. Implications of these results for theory and research are offered.     

Acquired autoimmune thrombocytopenia post-bone marrow transplantation for severe combined immunodeficiency

Children with severe combined immunodeficiency (SCID) have profoundly diminished humoral and cellular immunity resulting in death during infancy unless immune reconstitution occurs by bone marrow transplantation (BMT). Thrombocytopenia post-bone marrow transplantation can be seen in relation to infection, graft-versus-host disease (GVHD) and rarely, as an autoimmune phenomenon due to immune dysregulation. We report two cases of severe AITP following BMT for SCID. Both cases developed large intracerebral hemorrhages from which one died. Autoimmune thrombocytopenia in this setting can be life-threatening and we recommend early and active intervention.